The present invention lies in the field of railborne track vehicle management. More specifically, the invention relates to a method and a system for preventing the overfilling of a track system which is divided into track sectors and which is modeled in a route level with routes and a signal tower level with route segments. The levels are connected in order to request the setting of a route segment and to signal train positions, and a train position is determined by a train identifier, which identifies a train, and a track sector.
The expedient and reliable setting up and release of route segments for track-bound vehicles, referred to below as trains, are brought about by train services using operative methods. The selection of the track for the formation of route segments is affected by real operating conditions in a variety of ways. Examples of this are: operational effects, the composition of trains and in particular their length, the failure of track sectors due to defects.
The safety devices, referred to below as signal towers, which are used in the setting-up process ensure that only route segments that cannot lead to the traveling trains being put at risk are set up. However, the signal towers do not prevent route segments being set up which can impede or block trains from traveling onward. In such a case the track system is overfilled. Overfilling can be eliminated only by moving a train in reverse. This gives rise to time-consuming maneuvers with corresponding undesirable consequences for the timetable and the commercial operations.
In modern operative operational control centers, powerful control systems are increasingly performing routine control operations of the train service. In a control system, a unique train identifier that is used once throughout the timetable and an associated individual route through the track system are programmed for each traveling train, the train identifier usually being recorded as a train number. The train control system detects, as part of the control system, the respective position of the train and automatically sets up the next route segment for the onward travel of the respective train. The stimulus for the setting up of the route segment is given by the traveling train itself. Its position is continuously registered in the control system. In this way, the sequence of the route segments that are set up is directly dependent on the current trains journey. When there are unfavorable chronological conditions, the setting up of routes can lead to blocking owing to overfilling. So that the advantages of automatic train control can be utilized in all situations, the train control system must be able to foresee possible blockages and not set up the corresponding route segments, or set them up after a delay.
Before a route segment is set up, i.e. before a setup request is output to a signal tower, the train control system must check the effects in terms of overfilling of the track system. FIG. 1 illustrates a route level I: a view of the train control system; and a switchgear level or signal tower level II: view of the signal tower equipment. So that the route segments continue to be set up in good time, it must be possible to make the decision about the reliability of a route segment without delay.
A decision method which has a simple combinatory logic and which simulates the possible sequences of the train journeys requires a very large number of working steps. The trains and the track topology have to be taken into account completely in such a method.
Given n trains with a route length of m route segments each, a computational expenditure of the order of magnitude of nmxc3x97n process steps is necessary.
It is accordingly an object of the invention to provide a congestion prevention system and method, which overcome the above-mentioned disadvantages of the heretofore-known devices and methods of this general type and which provides a method which detects, with a smaller degree of computational expenditure, possible congestion, i.e., overfilling, before route segments are securely set up in terms of signaling equipment.
With the foregoing and other objects in view there is provided, in accordance with the invention, and in the context of a track system organized with track sectors and having a route level with routes and a switchgear level with route segments, the route level and the switchgear level being coupled for requesting a setting of a route segment and to signal train positions, a congestion prevention method for preventing an overfilling of the track system. The novel method comprises the following steps:
defining train positions of trains on the track system with a train identifier and a track sector; and
prior to setting a requested route segment for a given train, querying the route level to determine, by checking train positions, whether the given train is allowed to travel on the track sectors to be used for the requested route segment, without the track system becoming congested.
The method according to the invention has the following advantages, inter alia:
In the track system which is to be protected against overfilling, the automatic setting up of route segments is permitted only if the track system is not overfilled as a result, i.e. all the trains can reach their programmed destination.
The method according to the invention indirectly contributes to the safety of the railway traffic in that unusual maneuvers for disentangling trains are avoided.
The small number of working steps required to assess the situation permits the use of the method in control systems in a relatively large track system to be protected without disadvantageous effects on the prompt setting up of the route segments.
In accordance with an added feature of the invention, the step of checking a train position comprises the following substeps, to be performed in the route level:
a) storing a first dependency according to which a new train position cannot be reached until the train has reached a track sector that directly precedes the route, the first dependency being defined as a compulsory sequence of two train positions;
b) checking, for a variation of two trains, whether a reference location of a first train prevents the route of a second train being traveled on resulting in a second dependency, and storing the second dependency;
c1) generating, for all the trains, new dependencies by applying a transitivity from the stored dependencies, and storing the new dependencies; and
c2) checking the new dependencies whether a compulsory sequence according to which the first train must travel to a first track sector before the second train can travel to a second track sector.
In accordance with an additional feature of the invention, steps c1) and c2) are repeatedly executed for all trains until no further new dependencies can be generated or until no train can reach a destination predefined by its route.
In accordance with another feature of the invention, there is located a reference location of a train with respect to another train between a signaled position and a next controlling track sector on a route thereof, and defining a controlling track sector as a start of a route segment requested from the route level.
In accordance with a further feature of the invention, the method comprises:
carrying out step a) for all the trains; and
carrying out step b) for all possible variations of two trains.
In accordance with again an added feature of the invention, the method comprises:
storing timetable dependencies of the trains and predefined train sequences as dependencies; and
inserting the stored dependencies for the respective trains before performing step c).
With the above and other objects in view there is also provided, in accordance with the invention, a congestion prevention system for preventing an overfilling of the track system. The congestion prevention system comprises:
a process module containing means for querying the route level to determine train positions in the track system, and upon receiving a request for setting a given route segment for a given train, to determine whether the given train is allowed to travel on the track sectors to be used for the requested route segment, without causing the track system to become congested.
In accordance with yet an added feature of the invention, the process module, for checking the train positions in/the route level, contains:
a first sequence module for storing a dependency according to which a new train position cannot be reached until the train has reached a directly preceding track sector on the route, the dependency being defined as a compulsory sequence of two train positions;
a relation module for checking for two trains whether a reference location of a first train prevents the route of a second train from being traveled on and for storing a result as a dependency;
a transitivity module for generating and storing new dependencies by applying a transitivity from stored dependencies; and
a second sequence module connected to the transitivity module for checking whether there is a compulsory sequence according to which the first train must travel to a first track sector before the second train is allowed to travel to the second track sector.
In accordance with yet an additional feature of the invention, there is provided an iteration module, superordinate to the transitivity module and the second sequence module, for repeatedly carrying out an iteration for all the trains until no further new dependencies can be generated or until no train can reach the destination predefined by its route.
In accordance with yet another feature of the invention, the reference location is defined in the relation module, according to which the reference location of a train with respect to another train is located between the signaled position and the next controlling track sector on a route thereof, and a controlling track sector is defined as the start of a route segment requested from the route level.
In accordance with yet a further feature of the invention, the system includes a second iteration module, superordinate to the first sequence module, for carrying out an iteration for all the trains, and a third iteration module, superordinate to the relation module, for carrying out an iteration for all the variations of two trains.
In accordance with a concomitant feature of the invention, there is provided a data module that stores timetable dependencies of trains and predefined train sequences as dependencies, and a deployment module that inserts the stored dependencies for respective trains and feeds the stored dependencies to the transitivity module.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method and a system for preventing overfilling of a track system, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.